Microbeams under Mechanical Shock and Electrostatic Actuation Accounting for the Effects of Circuit Board and Package Motion

提出的研究的目的是推动微电子机械系统（MEMS）的发展前沿，探索机械冲击，非线性静电力，以及在MEMS器件的封装和印刷电路板（PCB）的运动之间的复杂的相互作用。 由于其小尺寸和高功能性，MEMS器件可以提供比传统传感器和致动器系统更高的成本、可制造性和可靠性。然而，限制MEMS商业化的一个关键问题是它们在受到机械冲击时的性能。 此外，MEMS发展的一个关键标准是它们在跌落到硬表面时的性能和生存能力;这对于便携式和手持设备尤其如此。 这种冲击可以在承载MEMS器件的PCB中引起弯曲运动。这种运动可以传递到微结构，导致其崩溃或错误的功能，例如在MEMS传感器的情况下给出错误的测量。此外，MEMS中的冲击负载可引起静摩擦和相关的短路问题。 该项目将在冲击/跌落载荷和非线性静电力的组合下对微梁进行建模、表征和测试，并考虑PCB和包装运动。 本文将重点讨论两种常用的MEMS微梁结构：夹持-夹持微梁和夹持-自由微梁，并采用基于非线性Euler-Bernoulli梁模型的降阶模型进行理论研究。 我们的理论结果将通过表征和测试不同水平的静电驱动和机械冲击载荷下的微加工硅梁进行验证。这项研究将有助于解释文献中报道的许多故障，并将允许设计人员避免它们，设计改进和更可靠的MEMS器件。这项工作将揭示机械冲击对常见但很少理解的动态吸合现象的影响的重要信息。 此外，这项研究的结果将提高许多基于微束的MEMS传感器和致动器的可靠性和商业可行性，这些传感器和致动器用于我们日常生活中的广泛应用，例如汽车。研究结果也将被用来调查一种新的技术的智能可调微动开关的加速度触发的可行性。 这些开关的可调性质允许针对各种触发需求定制设备，并且可能导致当前不可预见的未来应用和产品。 本研究将训练两名研究生对微机电系统微结构的建模、仿真、表征和测试。 这项研究的知识将支持MEMS动力学新课程的开发。 此外，该项目将在项目期间培训少数民族本科生，使他们接触这一新的研究领域，并鼓励他们进入研究生院。

The aim of the proposed research is to push the frontiers of micro-electro-mechanical systems (MEMS) development by exploring the little understood complex interaction between mechanical shock, nonlinear electrostatic forces, and the motion of the package and printed circuit board (PCB) in MEMS devices. Because of their small size and high functionality, MEMS devices can offer cost, manufacturability, and reliability advantages over traditional sensors and actuators systems. However, a critical issue limiting the commercialization of MEMS is their performance when subjected to mechanical shock. In addition, a crucial criterion for the growth of MEMS is their performance and survivability when dropped on hard surfaces; this is especially true for portable and handheld devices. Such an impact can induce bending motion in the PCB carrying the MEMS device. This motion can be transmitted to a microstructure leading to either its collapse or to a false function, such as by giving wrong measurements in the case of MEMS sensors. Also, shock loads in MEMS can induce stiction and related short circuit problems. This project will model, characterize, and test microbeams under combined shock/drop loads and nonlinear electrostatic forces and accounting for the PCB and packaging motion. Two commonly used MEMS microbeam configurations will be focused on: clamped-clamped and clamped-free microbeams.Reduced-order models based on the nonlinear Euler-Bernoulli beam model will be used for the theoretical investigation. Our theoretical results will be verified by characterizing and testing micromachined silicon beams under various levels of electrostatic actuation and mechanical shock loads.This research will help explain many of the failures reported in the literature, and will allow designers to avoid them and design improved and more reliable MEMS devices. This effort will reveal significant information about the effect of mechanical shock on the common, but rarely understood, dynamic pull-in phenomenon. In addition, the results of this research will improve the reliability and commercial viability of many microbeam-based MEMS sensors and actuators, which are used in a wide spectrum of applications in our everyday life, such as in automobiles. The results will also be used to investigate the feasibility of a new technology of smart tunable microswitches triggered by acceleration. The tunable nature of these switches allows for tailoring of the device for various triggering needs and may lead to future applications and products currently unforeseen. This research will train two graduate students on the modeling, simulation, characterization, and testing of MEMS microstructures. Knowledge from this research will support the development of a new course on the Dynamics of MEMS. Also, this project will train undergraduate minority students over the duration of the project to expose them to this new area of research and encourage them to attend graduate school.